Require bike helmets? There's not enough safety data

A bill in the state Legislature would require adult cyclists in California to wear a bike helmet. Above, cyclists attend CicLAvia on Martin Luther King Boulevard on Dec. 7, 2014. (Los Angeles Times)

This much is obvious: Wearing a bicycle helmet is safer than not wearing one. But so far, the evidence is mixed on how much safer it is. A bill in the Legislature to mandate helmets for all bicyclists is based less on evidence of significant benefit than on the mantra that it's worthwhile if even a single life is saved.

That's not how good safety policy is made. If it were, the state would require pedestrians to wear body armor; after all, five times as many pedestrians are killed in street accidents than are bicyclists.

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The intentions behind SB 192, authored by Sen. Carol Liu (D-La Canada Flintridge), are laudable, and many of the objections raised by bicycling enthusiasts are laughable — such as the idea that mandatory helmets would make bicycling appear more dangerous and thus discourage people from trying it. Yet supporters of Liu's bill have been unable to make a solid case for requiring helmet use by adults because they have no real idea how many injuries — or deaths — would likely be prevented.

Just as with seat belt and motorcycle helmet laws, a balance must be struck between allowing adults to make their own decisions about risks and protecting public safety. Obviously if many, many lives can be saved by a new mandate, that would be a strong argument in favor. But in the case of bicycle helmets, the proper balance is hard to strike because research is incomplete and often contradictory. Some studies show no real effect from helmet laws, whereas at least one shows a 20% to 30% reduction in deaths.

A study released in October 2014 by the Governors Highway Safety Assn. found that two-thirds of the bicyclists who died in accidents nationwide from 2010 to 2012 were not wearing helmets. At first glance, it might look as though California could save about 80 lives a year — two thirds of the more than 120 who die in such accidents in the state. But a poll by Consumer Reports found that 58% of U.S. adults don't regularly wear helmets for bicycling — which would suggest that a cyclist without a helmet is only slightly more likely to die than one with a helmet.

Figures vary widely from one report to another, and there appears to be no reliable information on what percentage of California bicyclists don't wear helmets, or on which fatalities or serious injuries could have been avoided with helmets.

Before the Legislature can reasonably decide whether to approve a helmet law, it first must know what the benefits would be. Liu would be better off amending her bill so that it directs the California Office of Traffic Safety to conduct a detailed study of helmet use, and then basing future legislation on solid facts instead of good intentions.